Nowadays, shredders are widely used to cut sheet-like articles. If a relatively thick article whose thickness is beyond an acceptable range (for example a thick paper or a compact disc) is shredded, the thick article is readily jammed. Under this circumstance, the shredder has a usage problem or even a breakdown. For avoiding the occurrence of the jamming event, a thickness triggering device is often mounted in the shredder to determine whether the article to be shredded is beyond the acceptable range.
FIG. 1 is a schematic perspective view illustrating a shredder having a thickness triggering device according to the prior art. The shredder 100 includes an entrance 101, a shredding path 102, a sustaining element 103, a thickness sensing module 104, a driving assembly 105, a transmission gear set 106 and a shredding knife assembly 107. The entrance 101 is disposed above the shredding path 102. The sustaining element 103 is arranged at a side of the shredding path 102. The thickness sensing module 104 is disposed behind the sustaining element 103. As shown in FIG. 1, the thickness sensing module 104 includes a light emitter 1041 and a light receiver 1042. The thickness sensing module 104 and the sustaining element 103 are collectively referred as a thickness triggering device. The shredding knife assembly 107 is disposed at the outlet of the shredding path 102. The transmission gear set 106 is interconnected between and engaged with the shredding knife assembly 107 and the driving assembly 105. As a consequence, the shredding knife assembly 107 can be driven by the driving assembly 105 to implement a shredding operation.
The operation of the shredder 100 will be illustrated as follows. First of all, an article (not shown) to be shredded is introduced into the shredding path 102 through the entrance 101. When the article is in contact with and sustained against the sustaining element 103, the sustaining element 103 is shifted backwardly to result in a shift distance with respect to its original place. In the thickness sensing module 104, the light emitter 1041 continuously emits the sensing light and the sensing light is received by the light receiver 1042. In a case that the sustaining element 103 fails to completely shelter the sensing light, the article is permitted to feed through the shredding path 102 so as to perform a shredding operation. Whereas, if the sensing light is sheltered by the sustaining element 103, the shredding operation of the shredder 100 is interrupted.
That is, in the case that the shift distance of the sustaining element 103 is not sufficient to completely shelter the sensing light emitted from the light emitter 1041, the thickness of the article is acceptable by the shredder 100. Under this circumstance, the article is continuously advanced in the shredding path 102. In addition, the shredder 100 has a shredding sensor (not shown) under the sustaining element 103. When the advancing article approaches the shredding knife assembly 107, the shredding sensor will detect the presence of the article. Meanwhile, the transmission gear set 106 is driven by the driving assembly 105 and begins to rotate. Upon rotation of the transmission gear set 106, the shredding knife assembly 107 is driven to implement a shredding operation.
As previously described, by using the sustaining element 103 and the thickness sensing module 104, the usage status of the shredder 100 may be determined according to the thickness of the article to be shredded. In other words, the sustaining element 103 and the thickness sensing module 104 are advantageous of avoiding the problem of causing jammed paper so as to extend the operating life of the shredder 100.
However, this shredder 100 still has some drawbacks. For example, the torsion force of the shredding knife assembly 107 is dependent on the width of the article to be shredded. As the width of the article is increased, the torsion force of the shredding knife assembly 107 is increased and thus the shredding knife assembly 107 is possibly fractured or damaged. For decreasing the loading of the shredding knife assembly 107, a wider article needs to be relatively thinner. As previously described, the thickness triggering device of the shredder 100 is capable of determining whether the article is beyond a specified thickness. If a wider article having an acceptable thickness is introduced into the shredding path 102, the possibility of causing the jamming event or fracturing the shredding knife assembly 107 is increased because the torsion force exerted on the shredding knife assembly 107 is increased.